Method and device for handling inconsistency of PSC states between two ends

Abstract

The present invention discloses a method and an associated networking device for eliminating inconsistency of PSC states between two ends of a communication tunnel. The method comprises the steps of: receiving a PSC message from another networking device (S 410 ); detecting a local PSC state of the networking device (S 420 ); determining whether the received PSC message is an NR message and the detected local PSC state is a DNR state (S 430 ); and changing the local PSC state from the DNR state to a Normal state (S 440 ), if it is determined that the received PSC message is an NR message and the detected local PSC state is a DNR state.

What is claimed is: 
     
       1. A networking device, comprising:
 a transceiver configured to receive a Protection State Coordination (PSC) message from another networking device; 
 a state detecting unit configured to detect a local PSC state of the networking device; 
 an inconsistency identifying unit configured to determine whether the received PSC message is a No Request (NR) message and the detected local PSC state is a Do-not-Revert (DNR) state; 
 an inconsistency removing unit configured to change the local PSC state from the DNR state to a normal state, if the inconsistency identifying unit determines that the received PSC message is an NR message and the detected local PSC state is a DNR state; and 
 a traffic path selecting unit configured to transport traffic using a working path instead of a protection path to the other networking device, if the local PSC state of the networking device is changed to the normal state. 
 
     
     
       2. The networking device according to  claim 1 , wherein the transceiver is further configured to send an NR message to the other networking device, if the inconsistency removing unit changes the local PSC state from the DNR state to the Normal state. 
     
     
       3. The networking device according to  claim 1 , wherein the inconsistency removing unit is further configured to maintain the local PSC state, if the inconsistency identifying unit determines that the received PSC message is a DNR message and the detected local PSC state is a normal state. 
     
     
       4. The networking device according to  claim 1 , wherein the networking device is to have a working path and a protection path to the other networking device, wherein the local PSC state is to be normal when the working path is active, and wherein the local PSC state is to be DNR when the protection path is active. 
     
     
       5. The networking device according to  claim 1 , wherein when both the working path and the protection path fail, the working path recovers first and the protection path recovers second, the local PSC state is to be set to normal, and wherein when both the working path and the protection path fail, the protection path recovers first and the working path recovers second, the local PSC sate is to be set to DNR. 
     
     
       6. The networking device according to  claim 1 , wherein the networking device and the other networking device are to be in a multi-protocol label switching transport profile (MPLS-TP) network. 
     
     
       7. The networking device according to  claim 6 , wherein the networking device and the other networking device are to form a MPLS-TP tunnel. 
     
     
       8. The networking device according to  claim 1 , wherein the networking device and the other networking device are to be in a 1:1 linear protection group. 
     
     
       9. The networking device according to  claim 1 , wherein the NR message is to be assigned to a higher priority than the DNR state of the local PSC state. 
     
     
       10. A method in a networking device, comprising:
 receiving a Protection State Coordination (PSC) message from another networking device; 
 detecting a local PSC state of the networking device; 
 determining whether the received PSC message is a No Request (NR) message and the detected local PSC state is a Do-not-Revert (DNR) state; 
 if it is determined that the received PSC message is an NR message and the detected local PSC state is a DNR state,
 changing the local PSC state from the DNR state to a normal state; and 
 transporting traffic using a working path instead of a protection path to the other networking device. 
 
 
     
     
       11. The method according to  claim 10 , further comprising:
 sending an NR message to the other networking device, if the local PSC state is changed from the DNR state to the Normal state. 
 
     
     
       12. The method according to  claim 10 , further comprising:
 if it is determined that the received PSC message is a DNR message and the detected local PSC state is a normal state, maintaining the local PSC state. 
 
     
     
       13. The method of  claim 10 , wherein the networking device has a working path and a protection path to the other networking device, wherein the local PSC state is normal when the working path is active, and wherein the local PSC state is DNR when the protection path is active. 
     
     
       14. The method of  claim 10 , wherein when both the working path and the protection path fail, the working path recovers first and the protection path recovers second, the local PSC state is set to normal, and wherein when both the working path and the protection path fail, the protection path recovers first and the working path recovers second, the local PSC sate is set to DNR. 
     
     
       15. The method of  claim 10 , wherein the networking device and the other networking device are in a multi-protocol label switching transport profile (MPLS-TP) network. 
     
     
       16. The method of  claim 15 , wherein the networking device and the other networking device form a MPLS-TP tunnel. 
     
     
       17. The method of  claim 10 , wherein the networking device and the other networking device are in a 1:1 linear protection group. 
     
     
       18. The method of  claim 10 , wherein the NR message is assigned to a higher priority than the DNR state of the local PSC state.